8182

• UCREFRP Catalog Number: 8182
• Author: Bestgen, K. R. and L. W. Crist.
• Title: Response of the Green River Fish Community to Construction and Re-regulation of Flaming Gorge Dam. 1962-1996\
• USFW Year: 2000.
• Copyright Material: NO

METHODS
Collections of small- and large-bodied f shes were made from 1994-1996 to understand
the present distribution and abundance patterns of fishes in the Green River upstream of the
Yampa River (study objective 1). Drift net sampling of larvae and seine sampling in Green
River backwaters downstream of the Yampa River was added to more completely address that
objective. Water temperature and discharge data were used to understand the relationship of
physical factors to longitudinal distribution and abundance patterns of fishes in the regulated
portion of the Green River (objective 2). Discharge and temperature regimes associated with
specific dam operation events was related to changes in fish distribution and abundance patterns.
That information, combined with other available data from other systems in the upper Colorado
River basin (objective 3), was used to determine whether further changes in flow and temperature
regimes in the regulated reach of the Green River downstream of Flaming Gorge Dam may
benefit rare fishes (objective 4).
Collection ofsmall-bodied fish.-Low-velocity channel margin areas in Browns Park,
Lodore Canyon, the lower 0.8 km of the Yampa River, and Island and Rainbow parks was
sampled with seines (1.3 and 4.6 m length, 1.6 and 4.8-mm mesh). Seine sampling in summer
and autumn 1994 included Browns Park, Lodore Canyon, and the lower Yampa River. Seining
in summer and autumn 1995 included Browns Park, lower Lodore Canyon, Island and Rainbow
parks, and the lower Yampa River. Habitat types sampled were mostly backwaters, but channel
margin eddies and low velocity runs and pools were also sampled. More sampling effort was
expended in larger habitat areas and less in smaller ones so that effort expended was
approximately equal across different-sized areas. Riffles in the lower portion of Lodore Canyon
and in the Yampa River were "kick-seined", whereby substrate was vigorously disturbed and
dislodged fish were captured in a stationary downstream seine. Samples were preserved in 10
fonnalin and identified at the Larval Fish Laboratory, Colorado State University.
Drift net samples collected in the Green River just upstream of the Yampa River in 1993,
1994, and 1995 were used to describe species composition and abundance patterns of larvae
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